Variations in Damp Heat-Induced Degradation Behavior of Sputtered ZnO Window Layer for CIGS Solar Cells

F. J. Pern, B. To, S. H. Glick, R. Sundaramoorthy, C. DeHart, S. Glynn, C. Perkins, L. Mansfield, T. Gessert

Research output: Contribution to conferencePaperpeer-review

11 Scopus Citations

Abstract

This paper presents our recent observations on variations in properties and damp heat (DH)-induced degradation behavior for single-layer 2%Al-doped ZnO (AZO) and bilayer ZnO (BZO), which comprises 0.1-μm intrinsic ZnO (i- ZnO) and AZO, deposited on glass substrates using the same sputtering system and essentially identical deposition conditions. BZO films with 0.12-μm AZO have been used on the National Renewable Energy Laboratory's (NREL's) high-efficiency CuInGaSe2 (CIGS) solar cells for years. For the as-deposited BZO films, the most apparent variations appeared in notable peak shift in transmittance and reflectance spectra and ZnO (002) peak intensity and peak position in X-ray diffraction. Location of substrates placed on the substrate holder platform contributed partly to the variations. For the DH-degraded AZO and BZO, earlier films became highly resistive, porous, and 10∼20 X thicker and showed flattened transmittance spectra caused by a loss of free-carrier absorption. However, recent DH-exposed AZO and BZO films also became highly resistive but exhibited only small changes in transmittance spectra, while the columnar grain structure and film thickness remained nearly unchanged without porous features, but with granular particles formed on the surfaces that increased in size with lengthening DH exposure time.

Original languageAmerican English
Number of pages12
DOIs
StatePublished - 2010
EventReliability of Photovoltaic Cells, Modules, Components, and Systems III - San Diego, CA, United States
Duration: 3 Aug 20105 Aug 2010

Conference

ConferenceReliability of Photovoltaic Cells, Modules, Components, and Systems III
Country/TerritoryUnited States
CitySan Diego, CA
Period3/08/105/08/10

NREL Publication Number

  • NREL/CP-520-48902

Keywords

  • Al-doped ZnO
  • Bilayer ZnO
  • CIGS solar cells
  • Damp heat test
  • Intrinsic ZnO
  • Performance reliability

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